Natural Radioactivity Levels in the Area around the Uranium Deposit of the Bahi District in Dodoma Region, Tanzania

In this study samples of soil and water from different villages in the Bahi wetlands were analyzed for radioactivity levels of 226Ra, 232Th and 40K using gamma ray spectrometry. The mean activity concentration of 226Ra, 232Th and 40K in soil were found to be highest in the northern zone of the study area compared to the central and southern zones. The northern zone includes the Kisalalo uranium deposit of which exploration is still going on. The mean activity concentrations of 226Ra, 232Th and 40K in soil samples from northern zone were 37.3±0.7, 51.1±0.9 and 874.9±9.0 Bqkg-1, respectively. The Central Zone had the mean activity concentrations of 226Ra, 232Th and 40K as 23.4±0.5, 25.8±0.5 and 495±5 Bqkg-1, respectively, while that from southern zone were 25.2±0.5, 37.3±0.7 and 368±4 Bqkg-1, respectively. In water samples, the activity concentrations of 226Ra were below the detection limit (0.11 Bql-1) for the system used in this study. The concentrations of 232Th and 40K were found to range from < 0.07 to 0.740±0.003 Bql-1 and < 1.01 to 4.36±0.05 Bql-1, respectively. The average concentrations of 226Ra and 232Th in drinking water samples from the study area were found to be lower than the guidance levels of these radionuclides (1.0 Bql-1 for 226Ra and 232Th) in drinking water recommended by the WHO.